November 30, 2004

In phylogenetic systematics one of the necessary preconditions for the recognition of a taxon is its monophyletic status. In other words, members of a taxon must share common descent, and not just relative similarity as in phenetics.

If three groups of organisms A, B, C are such that A and B are more similar to each other than they are to C, then phenetics would consider classifying A and B in one taxon and C in another. By contrast, phylogenetics would try to establish whether A and B share common characters derived from an ancestor that was not an ancestor of C. If it turns out e.g., that B and C have such an ancestor, then B and C should be grouped together, even though B is closer to A than to C.

It has long been established that human beings can be grouped into clusters corresponding to major "continental" populations. This has been achieved using cranial traits, classical polymorphisms, as well as more recently large numbers of microsatellites. Therefore, we are justified in thinking about the existence of human races in the phenetic sense.

However, recent advances in phylogeography, especially based on uniparentally transmitted markers on the Y chromosome and mtDNA have shown that human continental populations which correspond to phenetic races such as "Caucasoids", "Negroids", "Mongoloids", etc. do not correspond to monophyletic groups.

For example, almost 9 out of 10 Ainu trace their paternal lineage to an ancestor who has also fathered approximately 9 out of 10 Moroccans and South African Bantu. That man, who first carried the YAP mutation, lived either in Asia or Africa, and yet his descendants belong to three of the major human races.

Similarly, 9 out of 10 Basques are descended from a man who has also fathered 9 out of 10 Kets from Siberia and 9 out of 10 Maya Indians from America. That man, founder of haplogroup P thus has descendants who belong to two of the major human races (or three, if Amerindians are considered as separate from Asian Mongoloids).

Thus, despite the close proximity between, e.g., Spain and Morocco, and the genetic and phenotypic similarity of their inhabitants, who are considered to belong to the Caucasoid race, it is the case that phylogenetically, Spanish Basques and Mayan Indians share recent ancestry not shared by Moroccan Berbers, and conversely, Moroccan Berbers share recent ancestry with South African Bantu not shared by Basques.

Should we then acknowledge the existence of a "YAP race", or a "P race" on the basis of these observations? Not at all, since by examining other phylogenetically informative systems, e.g., mtDNA, it turns out that Basques and Moroccans are phylogenetically linked to the woman founder of mtDNA haplogroup N, while Ainu and Mayans are linked to a woman founder of mtDNA haplogroup M.

In conclusion, human continental populations form groups of genetic and phenotypic similarity, and these groups can be considered races in the phenetic sense. However, these groups are not monophyletic, hence in the cladistic sense they should not be considered as valid taxa. Since the principle of common descent is generally applied in modern systematics (or at least it should!), I think it's best not to recognize human subspecies.

We may still however speak of human races as clusters of biological similarity, or as ecotypes, if we keep in mind the understanding that the commonly recognized races are not phylogenetically justified.

November 26, 2004

It has long been established that Neanderthals were phyletically distinct from humans, but a new study estimates just how much admixture between the two species might have taken place during their cohabitation of Europe.

PLoS Biol. 2004 Nov 30;2(12):e421 [Epub ahead of print]

Modern Humans Did Not Admix with Neanderthals during Their Range Expansion into Europe.

Currat M et al.

The process by which the Neanderthals were replaced by modern humans between 42,000 and 30,000 before present is still intriguing. Although no Neanderthal mitochondrial DNA (mtDNA) lineage is found to date among several thousands of Europeans and in seven early modern Europeans, interbreeding rates as high as 25% could not be excluded between the two subspecies. In this study, we introduce a realistic model of the range expansion of early modern humans into Europe, and of their competition and potential admixture with local Neanderthals. Under this scenario, which explicitly models the dynamics of Neanderthals' replacement, we estimate that maximum interbreeding rates between the two populations should have been smaller than 0.1%. We indeed show that the absence of Neanderthal mtDNA sequences in Europe is compatible with at most 120 admixture events between the two populations despite a likely cohabitation time of more than 12,000 y. This extremely low number strongly suggests an almost complete sterility between Neanderthal females and modern human males, implying that the two populations were probably distinct biological species.

November 24, 2004

This paper found that group differences between natives and immigrants in the Netherlands were correlated with cognitive complexity of the tasks performed: bigger differences for more cognitively complex tasks.

Personality and Individual Differences (Article in Press)

Immigrant-majority group differences on work-related measures: the case for cognitive complexity

Jan te Nijenhuis et al.

Abstract

Comparisons on work-related measures of immigrants and majority group members in general result in less positive outcomes for immigrants. These findings are usually thought to be caused by various cultural factors. We hypothesized that the more cognitively complex the measures, the larger group differences become. The research sample consisted of 78 immigrant and 78 ethnic Dutch trainee truck drivers. For 23 work-related measures the correlation between standardized group differences and measures of cognitive complexity was r = .664 (p = .000). This strongly suggests that besides cultural factors individual differences in the ability to deal with cognitive complexity is an important factor in explaining group differences.

November 23, 2004

The following article seems to confirm, on the basis of dental traits, the hybrid origin of Southeast Asians, with the earliest inhabitants being Australoids, to which Mongoloids were later added, starting probably with the Neolithic.

It seems to me that in South and Southeast Asia, and perhaps in South Arabia to the west, and stretching into Oceania in the east, the earlier inhabitants were of an old, pigmented subequatorial "Paleo-Asian" type. Over this Paleolithic stratum, the main Eurasiatic races were added: Caucasoids in Arabia and India, and Mongoloids in Southeast Asia.

American Journal of Physical Anthropology (Early View)

Dental perspectives on the population history of Southeast Asia

Hirofumi Matsumura et al.

ABSTRACT

This article uses metric and nonmetric dental data to test the two-layer or immigration hypothesis whereby Southeast Asia was initially occupied by an Australo-Melanesian population that later underwent substantial genetic admixture with East Asian immigrants associated with the spread of agriculture from the Neolithic period onwards. We examined teeth from 4,002 individuals comprising 42 prehistoric and historic samples from East Asia, Southeast Asia, Australia, and Melanesia. For the odontometric analysis, dental size proportions were compared using factor analysis and Q-mode correlation coefficients, and overall tooth size was also compared between population samples. Nonmetric population affinities were estimated by Smith's distances, using the frequencies of 16 tooth traits. The results of both the metric and nonmetric analyses demonstrate close affinities between recent Australo-Melanesian samples and samples representing early Southeast Asia, such as the Early to Middle Holocene series from Vietnam, Malaysia, and Flores. In contrast, the dental characteristics of most modern Southeast Asians exhibit a mixture of traits associated with East Asians and Australo-Melanesians, suggesting that these populations were genetically influenced by immigrants from East Asia. East Asian metric and/or nonmetric traits are also found in some prehistoric samples from Southeast Asia such as Ban Kao (Thailand), implying that immigration probably began in the early Neolithic. Much clearer influence of East Asian immigration was found in Early Metal Age Vietnamese and Sulawesi samples. Although the results of this study are consistent with the immigration hypothesis, analysis of additional Neolithic samples is needed to determine the exact timing of population dispersals into Southeast Asia.

November 20, 2004

The average height of the new generation in Greece has increased to 1.78 for men and 1.66 for women. This means that today's 20-year-old men are 3cm taller than 40-year-olds and 5cm taller than 50-year-olds, while 20-year-old women are 2cm taller than 40-year-olds and 3cm taller than 50-year-olds.

The article in Vita notes that the new generation owes its higher stature partly to the degrees of its parents: 20-year-old youths with parents having a university degree are slightly taller than those whose parents have graduated only from high school.

However, experts believe that the average stature of the population will begin to stabilize in our country in the next few decades. In other European countries, the height increase has slowed down significantly: in Sweden, the average height of recruits is stable (1.79) in the last 17 years, while in Holland, the change per decade is now limited to 1.3cm, while up to 1980 it was 2-3cm.

Differentiation of the Mitochondrial Subhaplogroup U4 in the Populations of Eastern Europe, Ural, and Western Siberia: Implication to the Genetic History of the Uralic Populations

B. A. Malyarchuk

Phylogenetic relationships between the sequences of the mitochondrial DNA (mtDNA) hypervariable segment 1, belonging to subhaplogroup U4, were examined in the populations of Eastern Europe, Ural, and Northwest Siberia. It was shown that the frequency of subhaplogroup U4, as well as its proportion in the U-component of the gene pools, increased eastwards, reaching maximum values in the populations of Northwest Siberia. Phylogenetic analysis it was showed that the appearance of specific U4-lineage (16113C–16356–16362) in the ancestors of Mansi was most likely caused by its divergence from the East European cluster 16356–16362 in the Late Upper Paleolithic (18566 ± 12915 years before present). Other U4 mtDNA lineages (16189–16356 and 16311–16356), typical mostly of the indigenous populations of Northwest Siberia (Mansi, Nganasans, and Kets) may have formed during the Neolithic–early Bronze Age (6055 ± 3599 years before present, on average). It seems likely that the isolation of ancient populations inhabiting the region between the Ob' and Yenisei rivers was the key factor, providing the appearance of the unique Caucasoid mtDNA lineages in their gene pools. These results were consistent with the traditional point of view on the mixed origin of the Finno-Ugric populations of the Volga–Ural region and West Siberia, resulted from the genetic relationships between the populations of Europe and Asia.

Restriction Polymorphism of Mitochondrial DNA in Koreans and Mongolians

M. V. Derenko et al.

Using the data on mitochondrial DNA (mtDNA) restriction polymorphism, the gene pools of Koreans (N = 164) and Mongolians (N = 48) were characterized. It was demonstrated that the gene pools were represented by the common set of mtDNA haplogroups of East Asian origin (M*, M7, M8a, M10, C, D4, G*, G2, A, B*, B5, F1, and N*). In addition to this set, mtDNA haplogroups D5 and Y were identified in Koreans while Mongolians possessed haplogroup Z. Only in Mongolians, a European component with the frequency of 10.4% and represented by the mtDNA types belonging to haplogroups K, U4, and N1, was identified. Phylogenetic and statistical analyses of the data on mtDNA variation in the populations of South Siberia, Central, and East Asia suggested the existence of interpopulation differentiation within these regions, the main role in which was played by the geographical and linguistic factors. Analysis of the pairwise FST distances demonstrated close genetic similarity of Koreans to Northern Chinese, which in turn, were clearly different from Southern Chinese populations. Mongolians occupied an intermediate position between the ethnic groups of South Siberia and Central/East Asia.

November 18, 2004

Genetic Structure of Hmong-Mien Speaking Populations in East Asia as Revealed by mtDNA Lineages

Bo Wen et al.

Abstract

Hmong-Mien (H-M) is a major language family in East Asia, and its speakers distribute primarily in southern China and Southeast Asia. To date, genetic studies on H-M speaking populations are virtually absent in the literatures. In this report, we analyzed genetic variations in the mtDNA HVS1 region and diagnostic variants in the coding regions in 537 individuals sampled from 17 H-M populations across East Asia. The results showed that the haplogroups that are predominant in the southern East Asia including B, R9, N9a, and M7 account for 63% (ranging from 45% to 90%) of mtDNAs in H-M populations. Furthermore, AMOVA, phylogenetic tree and principal component (PC) analysis demonstrate closer relatedness between H-M and other southern East Asians, suggesting a general southern origin of maternal lineages in the H-M populations. The estimated ages of the mtDNA lineages that are specific to H-M coincide with those based on archeological cultures that have been associated with H-M. Analysis of genetic distance and phylogenetic tree indicated some extent of difference between the Hmong and Mien populations. Together with the higher frequency of north-dominating lineages observed in the Hmong people, it is indicated that the Hmong populations had experienced more contact with the northern East Asians, consistent with historical evidence. Moreover, our data defined some new (sub-)haplogroups (A6, B4e, B4f, C5, F1a1, F1a1a, and R9c), which will direct further efforts to improve the phylogeny of East Asian mtDNAs.

November 17, 2004

You can tell a lot about people from their trash, but a new story from "New Scientist" shows how garbage can be used to trace the origins of sedentary communities. The existence of "dwellings" alone does not prove that these were used by a sedentary community, because it's possible that they were simply a temporary abode of a tribe of mobile individuals.

The main idea that researchers used is that humans established in a village community must devise a method of disposing trash to specified locations away from their habitation; otherwise the stuff just piles up! On the other hand, non-sedentary people can afford to throw the trash anywhere, since they will move out long before there's too much of it.

Using this type of reasoning, it was determined that the 12,000 year old Natufian dwellings at Wadi Hammeh 27 were used by non-sedentary hunter-gatherers, while true sedentism and garbage disposal is found only 9,200 to 8,000 years ago, together with the first agricultural communities.

This discovery strengthens the case that sedentism did not predate agriculture; it is more likely that it evolved at the same time as agriculture itself.

November 16, 2004

The Nazis’ occupation of Greece resulted in death, devastation, and the theft and destruction of countless cultural relics of the classical past

High-ranking officers of the German occupying forces stand on the Acropolis in May 1941. Despite promises to respect ancient Greek sites, the Acropolis in general, and the Parthenon in particular, were used as urinals.

By Yiannis Elafros - Kathimerini

The period of German, Italian and Bulgarian occupation in World War II left terrible scars, not only on the population — with hundreds of thousands dead, the deprivation, oppression and destruction — but also on Greece’s archaeological and cultural heritage. Trenches sliced through archaeological sites, museums and collections were destroyed or looted, while huge numbers of churches and monasteries were bombed or burnt by the occupation forces.

The Greek lands, which bear such obvious traces of history, were ground beneath the Nazis’ iron heel. From the Acropolis to Babylon, it is the fate of monuments to suffer during wars and occupations.

In a report published in 1946 by the Directorate of Antiquities and Historical Monuments, the Greek state attempted to record all the losses that took place during those dark years. Of the cultural artifacts stolen, few were returned after the war. Likewise, not all war reparations were paid.

Souvenirs

The Nazis invading Greece brought with them a passion for antiquity and an ideological viewpoint that placed the roots of the Aryan race in ancient Greece. The Wehrmacht had even supplied German soldiers with leaflets on the archaeological heritage of Greece and the importance, from their own standpoint, of archaeological sites, stressing that they must be left untouched.

But even in an army with the fanaticism and discipline of the Nazis, theory was distinctly remote from practice. Even high-ranking officers of the Wehrmacht did not hesitate to take something as a souvenir, should such an opportunity present itself.

There were also organized thefts, and even wholesale looting of antiquities, as in Elefsina. “When you have power over life and death, then it seems a simple matter to take a stone or make off with a statuette,” historian Hagen Fleischer told Kathimerini.

Parthenon libations

Not even the Acropolis, where the Germans did not hesitate to put German anti-aircraft guns, escaped. After protests by the Greek archaeological service, they withdrew their own guns but pushed the Italians to position their mortars and anti-aircraft searchlights there instead. Cement structures were even erected on the Sacred Rock by the German allies.

These were all taken down in February 1942, but, as the 1946 report said, “for the occupation forces, all the Acropolis monuments were urinals, with preference given to the Parthenon.”

Liberation did not end the depredations suffered by the Acropolis. In December 1944, British troops encamped on the Acropolis used it as a base for firing at the Communist-led resistance forces.

When the overall barbarity of the Nazi occupation is taken into account, people suffered much worse than the monuments. The German administration tried to keep up appearances, especially where the monuments of classical antiquity were concerned. There was a manifest attempt by the Nazis at an ideological exploitation of the ancient Greek heritage. A typical example was a personal order by Himmler for the commencement of intensive excavations at Ancient Sparta. It was hoped they would find Doric and pre-Hellenic monuments that obviously would be used to confirm Nazi theories of the Aryan race.

Formally, the Germans had handed over control of archaeological sites and excavations to the Greek archaeological service. But they wielded the real power, overriding whatever objections these straw men raised.

But a number of workers at museums and the archaeological services fought to save Greece’s antiquities. One of the most impressive stories in this struggle was the burial of all the Archaeological Museum of Athens’s most valuable material, a process that began with the commencement of the Greco-Italian war. A titanic undertaking that lasted six whole months, it was completed before the Germans entered Athens. The museum’s property was returned to it, unscathed, after the war.

Some areas, such as Crete, suffered worse than others. The island had the misfortune to have a governor who was also an amateur archaeologist. General Julius Ringel even organized digs at Knossos from which he lifted various valuable items. In 1942, he was transferred to the Eastern Front, where he would have probably have found little use for them.

Where the Germans were utterly ruthless was during the so-called “cleansing operations” — raids on the Greek countryside which resulted in huge devastation and massacres in a number of villages (Kalavryta, Distomo and others). These raids were more frequent in the last years of the occupation, in a response to increasing pressure by ELAS resistance fighters.

During this period, a large number of monasteries and churches were destroyed (Meteora, Aghia Lavra, Hosios Meletios, etc.), many of them dating to the Byzantine era and all containing important artifacts.

Apart from the Greek report, there is the official British report (“Works of Art in Greece, the Greek Islands and the Dodecanese: Losses and Survivals in the War,” London, HMSO, 1946), which said that, given the extent of the fighting and resistance, the damage done to the archaeological sites and monuments of classical antiquity was relatively slight. The same was not true of churches, which were frequently burned by Italian and German forces. The Bulgarians come in for special mention for the havoc they wreaked on the archaeological sites and museums of Eastern Macedonia and Thrace, which suffered heavily.

November 13, 2004

My reading of these records seems to indicate that most of them are of Jewish origin. There may be probably some bias, due to the greater representation among Ashkenazi Jews in the ysearch sample compared to Christian Eastern Europeans, but a search for haplogroup R1a reveals some names which sound non-Jewish, at least with my limited knowledge.

Classified ads in the newspaper Sydney's Child are saturated with couples appealing for an "angel" to help them have a family. Couples can go to the US, where it is legal to pay donors, but the cost can be up to $US25,000. But pro-family cultural attitudes in Greece mean a higher proportion of women there are happy to give eggs at the same time as their own treatment, said Denyse Asher, an IVF scientist from the Sydney fertility service that put the McAdams in touch with their Greek doctors.

Ms Asher said it was rare for older women to find a donor from their immediate circle. "If they're younger, their sisters and cousins are all in the same reproductive age group. But if they find themselves sitting here at 44, most of their friends and sisters are too."

Besides, taking an egg from a known person can raise complex issues. "You've got to work out what role they will have. Are they going to want to be at birthday parties and how do you feel about that?" said Ms Asher, who runs a Bondi Junction fertility service with her husband, Joel Bernstein.

She said they had referred more than 50 couples to the Greek clinic, of whom 76 per cent had become pregnant.

This paper shows a relationship between mitochondrial haplogroups and, amyotrophic lateral sclerosis, a neurodegenerative disease. The researchers found that individuals with mtDNA haplogroup I had a decreased risk for the disease. According to GeoGene, haplogroup I is labeled as "Asia Minor," perhaps reflecting its likely origin.

Could mitochondrial haplogroups play a role in sporadic amyotrophic lateral sclerosis?

Mancuso M et al.

Mitochondrial impairment has been implicated in the pathogenesis of the amyotrophic lateral sclerosis (ALS). Furthermore, mitochondrial-specific polymorphisms were previously related to other neurodegenerative diseases, such as Parkinson, Friedreich and Alzheimer disease. To investigate if specific genetic polymorphisms within the mitochondrial genome (mtDNA) could act as susceptibility factors and contribute to the clinical expression of sporadic ALS (sALS), we have genotyped predefined European mtDNA haplogroups in 222 Italian patients with sALS and 151 matched controls. Individuals classified as haplogroup I demonstrated a significant decrease in risk of ALS versus individuals carrying the most common haplogroup, H (odds ratio 0.08, 95% confidence interval 0.04-0.4, p < 0.01). Further stratification of the dataset by sex, age and site of onset of disease and survival failed to reach significance for association. Our study provides evidence of the contribution of mitochondrial variation to the risk of ALS development in Caucasians. Further it may help elucidate the mechanism of the mitochondrial dysfunction detectable in ALS, and may be of relevance in development of strategies for the treatment of this disease.

November 12, 2004

Whit Athey has written a nifty Y-haplogroup predictor. You enter your STR data, and the predictor gives you a score for various (mostly Caucasoid) haplogroups. This will be useful to any people looking to get a quick estimate of their probable haplogroup without having to dive into the technical literature for information. Alternatively, GeoGene and Trace Genetics offer haplogroup determination tests, and other labs let you test for particular SNPs after you get a regular STR test.

At least in my case, the Y haplogroup predictor seemed to work fine, even when I entered a small number of values.

November 11, 2004

I glanced through Stephen Oppenheimer's The Real Eve : Modern Man's Journey Out of Africa today. A pretty good book, covering both the Y-chromosomal and mitochondrial phylogeny of mankind, and seemingly less intellectually "lightweight" than some other rcent entries in the genre. On the minus side, the tendency of geneticists to give fanciful names to clades is very tiring, and I caught a few instances of Oppenheimmer trying to "fit" biblical genealogy with human phylogeny to justify his choices. On the plus side, any book that still uses terms like "Mongoloid" and "Australoid" shows a refreshing degree of acceptance of the traditional racial nomenclature. I didn't read enough to discover the obligatory "race doesn't exist" section -which has become quasi-obligatory in books on this subject- and I hope The Real Eve doesn't have one. All in all, I think it's a good primer on human genetic prehistory.

November 09, 2004

Continuing the previous post, it has struck me as interesting that the frequency of haplogroups R1a and Q in Altaian Turkic speakers is about 46/17 or a ratio of ~2.7, while in Ashkenazi Jews it is 12/5, or a ratio of ~2.4.

I haven't been able to dig up any reliable information about the ultimate origins of the Khazars in Asia, and many Turkic-speaking groups lack haplogroup Q, which is on the other hand found among Uralic-speakers, both in Siberia and in Hungary. Haplogroup Q is found at traces in Anatolia, making it possible that eastward moving Turkic speakers may have possessed this haplogroup. Even in Hungary, the Uralic-speaking Magyars were at the head of a confederacy which included Turkic speakers.

So, it seems likely at first hand that Turkic elements may have possessed some blend of R1a and Q in addition to other lineages. What the proportion of these in Khazars was is anyone's guess, but the similarity of the ratio of the two haplogroups in Ashkenazi Jews and Altaians is interesting.

Altaians also have 22.4% of haplogroup C, which is lacking in Ashkenazi, but this is probably due to the later westward moving of Altaic Mongolians in Genghis Khan times, which followed migrations of Turkic speakers.

Altaians also have traces of haplogroup N, which has also been detected in Ashkenazi, and is yet another piece of evidence of some "Asian" input.

If Proto-Khazars were similar to present-day Altaians minus haplogroup C, then they would have a frequency of about 59% R1a and 22% Q.

Therefore, it seems reasonable that an overall 5/22 = ~22% of such Proto-Khazar elements into the Ashkenazi Jewish population may be likely. But, the Khazars of Khazaria may themselves have been somewhat mixed with Western Eurasian elements, which would decrease their frequency of haplogroup Q.

All this is very speculative, and one would have to take a look at Altaian and Ashkenazi Jewish haplotypes within R1a and Q to check whether this theory is valid, but if it is, I would guess that about 1/4 male-mediated influence from a Khazarian source (with wide error margins!) may be just about right.

PS: The silence of researchers about the presence of haplogroup Q in the Ashkenazi is puzzling. I hope that someone is writing a paper on it, since Q is much more of a "smoking gun" of a Khazar connection than R1a which is much more problematic due to its fairly wide distribution in West Eurasia.

The authors formed teams of two, consisting of individuals of different cognitive ability and posed a learning task to them. Not surprisingly, teams with smart individuals learned more than teams with not-so-smart ones. If a team consisted of two smart individuals, then they both learned more than if paired with a not-so-smart individual. When a smart individual was paired with a not-so-smart one, then the not-so-smart individual did not benefit much from the presence of his smart team-mate.

This seems to me to be an extra argument for IQ homogeneity as a creator of wealth. IQ's influence on productivity is not direct but via the medium of learning; that is, high IQ individuals are useful if they acquire some productive skill, e.g., engineering. Ceteris paribus a society with a homogeneous IQ will form groups of similar-IQ individuals more frequently, and this will act as a catalyst, enhancing their mutual acquisition of knowledge. By contrast, in a heterogeneous society with the same average IQ as a homogeneous one, this amplifying effect will not be observed, unless some social mechanisms for cognitive segregation are in place.

Intelligence (In Press)

Ability-based pairing strategies in the team-based training of a complex skill: Does the intelligence of your training partner matter?

Eric Anthony Day et al.

Abstract

Intelligence researchers traditionally focus their attention on the individual level and overlook the role of intelligence at the interindividual level. This research investigated the interplay of the effects of intelligence at the individual and interindividual levels by manipulating the intelligence-based composition of dyadic training teams. Using a sample of 176 young adult males and a complex computer-based criterion task, homogeneous and heterogeneous dyadic training teams were created based on intelligence scores, and both team and individual performance were assessed throughout 10 h of training. Results indicated a strong additive influence of intelligence on team performance and a slightly positive nonadditive effect in uniformly high (HH)-ability teams. Trainees' individual skill acquisition was strongly correlated with the performance of their teams. However, nonadditive partner effects were observed such that high-ability trainees acquired significantly more skill when paired with high-ability partners instead of low- ability partners, but low-ability trainees benefited very little from being paired with high-ability partners.

November 08, 2004

Askhenazi Jews have about 5% of Y haplogroup Q [1], which is lacking in Sephardic Jews and is thus probably not of ancient Jewish origin.

Haplogroup Q is found in Asia in very high frequencies in several Uralic and Altaic groups [2], so it's possible that it represents an introgression of Khazar elements; the Khazars were a Turkic tribe.

November 05, 2004

If two-parent care has different consequences for the reproductive success of sons and daughters, then natural selection may favour adjustment of the sex ratio at birth according to circumstances that forecast later family structure. In humans, this partnership-status hypothesis predicts fewer sons among extra-pair conceptions, but the rival 'attractiveness' hypothesis predicts more sons among extra-pair conceptions, and the 'fixed-phenotype' hypothesis predicts a constant probability of having a son, regardless of partnership status. In a sample of 86 436 human births pooled from five US population-based surveys, I found 51.5% male births reported by respondents who were living with a spouse or partner before the child's conception or birth, and 49.9% male births reported by respondents who were not (χ2=16.77, d.f.=1, p < 0.0001). The effect was not explained by paternal bias against daughters, by parental age, education, income, ethnicity or by year of observation, and was larger when comparisons were made between siblings. To my knowledge, this is the first direct evidence for conditional adjustment of the sex ratio at birth in humans, and could explain the recent decline in the sex ratio at birth in some developed countries.

November 04, 2004

Evolutionary theory is partly based on mutation, a process which creates genetic variants, and selection, a process which favors or disfavors some of these variants. The intensity of selection may vary over time, e.g., may be higher during a famine, but do organisms always adapt at a constant rate, or is it possible that their ability to evolve, their "evolvability" is itself subject to natural selection?

Two authors from Rice University have recently written an article where they propose just that, citing many results which are explained by the assumptions of selectable evolvability. It now appears that the rate of genetic change should not be considered constant, but may rather fluctuate depending on selection pressure: as organisms find themselves in new or changed environments, they do not change only because of selection, but also because the propensity to mutate itself is encouraged. This is particularly clear when organisms undergo many successive episodes of changed environmental conditions.

Proc Natl Acad Sci U S A. 2004 Aug 10;101(32):11531-6.

Evolvability is a selectable trait.

Earl DJ, Deem MW.

Concomitant with the evolution of biological diversity must have been the evolution of mechanisms that facilitate evolution, because of the essentially infinite complexity of protein sequence space. We describe how evolvability can be an object of Darwinian selection, emphasizing the collective nature of the process. We quantify our theory with computer simulations of protein evolution. These simulations demonstrate that rapid or dramatic environmental change leads to selection for greater evolvability. The selective pressure for large-scale genetic moves such as DNA exchange becomes increasingly strong as the environmental conditions become more uncertain. Our results demonstrate that evolvability is a selectable trait and allow for the explanation of a large body of experimental results.

A new article looks at the origins of the Ossetians, a people of the Caucasus speaking Ossetian, a language of the Iranian branch of the Indo-European family. Researchers have studied Y chromosomes of North and South Ossetian, who live on either side of the Caucasus mountain range.

A few interesting observations from the article: Ossetians lack Y haplogroup C, which is found elsewhere in the Caucasus and in Asia Minor in small frequency, signifying intrusions of Altaic peoples such as Mongolians and Turks. North Ossetians do not possess a substantial frequency of Y haplogroup E, unlike South Ossetians. All Ossetian groups possess Y haplogroup J2, the main Neolithic marker, on the other hand haplogroup R1a, associated by some with the Kurgan people, is lacking in many Ossetian subgroups.

Annals of Human Genetics (Online Early)

Genetic Evidence Concerning the Origins of South and North Ossetians

Ivan Nasidze et al.

Summary

Ossetians are a unique group in the Caucasus, in that they are the only ethnic group found on both the north and south slopes of the Caucasus, and moreover they speak an Indo-European language in contrast to their Caucasian-speaking neighbours. We analyzed mtDNA HV1 sequences, Y chromosome binary genetic markers, and Y chromosome short tandem repeat (Y-STR) variability in three North Ossetian groups and compared these data to published data for two additional North Ossetian groups and for South Ossetians. The mtDNA data suggest a common origin for North and South Ossetians, whereas the Y-haplogroup data indicate that North Ossetians are more similar to other North Caucasian groups, and South Ossetians are more similar to other South Caucasian groups, than to each other. Also, with respect to mtDNA, Ossetians are significantly more similar to Iranian groups than to Caucasian groups. We suggest that a common origin of Ossetians from Iran, followed by subsequent male-mediated migrations from their Caucasian neighbours, is the most likely explanation for these results. Thus, genetic studies of such complex and multiple migrations as the Ossetians can provide additional insights into the circumstances surrounding such migrations.

Europe: We love to vacation there, if we can afford it. It's the cultural mecca many of us flock to, to awaken our senses and feed our souls. But Europe as a political entity? To Americans, it's just a creaky old set of governments presiding over a moribund economy marked by inflexible labor policies, bloated welfare bureaucracies and an aging, pampered populace. It's the state of Eurosclerosis, right?

Not anymore. Toss out that image of Europe as relic. On Friday, the heads of the 25 member nations of the European Union signed the European Constitution (to be ratified over the next two years by each state), effectively creating the first transnational political entity in history. These "United States of Europe" represent the rise of a new ideal that could eclipse the United States as the focus of the world's yearnings for well-being and prosperity. Yet our country is largely unaware of and unprepared for the vast changes that are quickly transforming the Old World and giving birth to what I call the new European Dream.

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Dienekes' Anthropology blog is dedicated to human population genetics, physical anthropology, archaeology, and history.

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